Skirt collision with body
Topology of your dress has to be even - try keeping all polygon in square shape and similar sizes.
Always use collide boxes to collide with your dress.
Don't use mesh cage on your dress unless your dress model is complicated.
Rig your dress to the armature first, and then pin the upper part of the dress, leaving the lower part to be sim. That's about 30% or more that needs to be pinned (half way up the thigh and anything above).
In cloth sim, Set structural to 5 and mass to 1, and start tweaking from there. These two are the crucial factors, Others only serve to improve its behavior. Also, in blender, a large step number doesn't necessarily mean it's better. A lot of times larger step number gives you worse result.
When you are ready to sim it, always start baking from a rest position!
When something's off, free your bake first before fixing it. If you don't free your bake first, your changes will not be applied.